


Whole

by outoftheashes



Series: Whole [1]
Category: Supernatural
Genre: Alternate Universe, Angst, Angst with a Happy Ending, Bossy Castiel, Bottom Sam, Butt Plugs, Depression, Dom Castiel, Exhibitionism, First Time, Fluff, Implied Bottom Dean, Jealousy, Multi, Nightmares (mentioned), Older Sibling Sam Winchester, Polyamory, Sastiel Big Bang 2016, Voyeurism, Younger Sibling Castiel, Younger Sibling Dean Winchester, implied switch Sam
Language: English
Status: Completed
Published: 2016-12-22
Updated: 2016-12-22
Packaged: 2018-09-11 00:48:25
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 8,574
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8946493
Author URL: https://archiveofourown.org/users/outoftheashes/pseuds/outoftheashes
Summary: When Cas is placed into twelve-year-old Sam's arms for the first time he forms an instant attachment with the toddler. Over the years Sam, Dean, and Cas become inseparable - until Sam goes off to college, that is. After Cas turns eighteen and Sam moves back home Dean’s distant and Sam misses him and how it used to be. One thing that remains the same? The bond Sam shares with Cas.





	

**Author's Note:**

> Thank you so much to my artist Nic. Your art is breathtaking and captures this story so completely. But you went above beyond being my artist. You were also my beta, the one that helped me brainstorm fix-its and so much more. Without you the end result would have been woefully lacking. 
> 
> Thank you Kate, Holly, Dean and Dale for being my cheerleaders. Without you I may have dropped out of the bang. 
> 
> I’d also like to thank archofimagine who gave me the plot bunny for this story and also happens to be a mod for the sastielbb, which is what this project was created for.

The day Amara puts Cas in Sam’s arms for the first time the two-year-old is wearing a shirt with a bumblebee on it.

“Hey, Cas,” he says awkwardly, because he doesn’t know this kid and it’s been awhile since Dean was so small. “How, uh, are you buddy? I’m Sam.”

The toddler says nothing.

“And this is Dean.” His little brother is holding onto his leg tightly so he’s an easy target - Sam tickles him with his free hand.

“ _My_ Sam.”

Sam snorts. _Dean, you possessive little shit._

Dean stares up at them seriously, waiting for a reply.

Cas is quieter than Sam’s used to a toddler being. Granted, the only toddler Sam has known well up to this point is Dean, but still. Shouldn’t they be loud and mildly irritating?

But the dark-haired boy is nearly silent as he watches him and Dean closely.

“Uh. Maybe we should go outside, huh?”

Cas keeps on staring and Sam’s almost ready to call it quits and put the kid down on the floor when Cas nods and points at the back door before grabbing Sam’s face with his chubby little hands.

Yeah, this kid is odd, but Sam can’t help but like him.

He gives Dean a once over to see how he’s doing and Dean beams.

“Sammy! Let’s play!” Dean crows, letting go of his big brother’s legs and claps his hands before speeding off to the back door.

He carries Cas over to his brother and opens the sliding glass door so all of them can head outside together. The toddler has a death grip on him so he’s not even afraid of dropping the little guy.

Dean’s zooming around the yard, already having a blast, but Cas won’t fucking let go of Sam and Sam’s not sure what the hell to do about that.

“Uh… Cas? Don’t you wanna get down on the ground and… you know. Play tag? Chase Dean?”

Cas shakes his head no, looking far too serious and understanding for a two-year-old. The look in his eyes is not something Sam can ignore and when he starts patting Sam’s arms he finally gets it.

“You wanna sit on my shoulders, Cas?”

Cas lifts his arms, confirming Sam’s thoughts.

“All right, Cas. Hang on.” Sam laughs and moves further out into the yard so he can be closer to Dean then maneuvers Cas onto his shoulders and the kid immediately starts hugging his head.

No way would he admit it out loud to his friends or dad, but a warmth spreads through Sam’s chest at the rightness of this moment, at Cas hugging him and his loud little brother running circles around them.

“I’m Batman, I’m Batman!” Dean yells and picks up speed, running even faster.

“Yeah, Dean. You’re Batman,” Sam agrees with a small laugh.

 

* * *

 

“He’s weird!” Dean accuses as Cas waddles around after him like a little duck. “Make ‘im stop, Sammy!”

Sam just came back from the toy store and _this_ is his welcome home.

“Aw c’mon, Dean! He just wants to play with you.”

Oh god, Sam _needs_ them to get along, for Dean to let them play together for more than two seconds.

He _loves_ Dean. Of course he does. And he’s already starting to care for Cas, too, but damn he needs space. He needs to _breathe_ for a minute. Sam’s not an adult and he’s certainly not a saint - he’s _twelve_. As much as he tries to fight it, he feels moments of impatience and it seems impossible, like Dean’s destined to hate Cas forever.

“Don’t like him followin’ me!” Dean insists.

Sam nods and picks Cas up.

“Hey, Cas. I got a present for you,” he murmurs, pulling out the big, fluffy bumblebee from the bag he’s carrying.

“Bee!” Cas laughs. He grabs the toy and immediately presses it against his face. “Good bee.

Sam swallows hard. “Y-yeah? You really like it, huh?”

“Bee, bee, bee,” Cas repeats, rubbing the stuffed bee along Sam’s cheeks. “Bee is friend.”

That reaction alone is worth the allowance spent to buy the toddler the present.

He carries them over to the couch and places Cas in his lap. He has a death grip on the bee and Sam feels elated, but lost all at once.

“You good now, Dean?”

Dean runs over to them and crawls up into Sam’s lap, suddenly uncaring of Cas’s closeness. He’s not quite broad enough for a toddler and four-year-old to share it without issue - especially when the four-year-old in question won’t stay still.

“ _My_ Sammy,” Dean says and he means business. The way he’s looking at him - and Cas - makes that perfectly clear.

“Yeah, Dean. Your Sammy.”

The tension in Dean’s body eases and he settles down.

It’s always been Sam and Dean. For four years of his life Dean has been the baby, he’s had Sam’s undivided attention, and now he has to share it with Cas. Now Cas is the youngest and Dad has made it clear that the toddler and Amara aren’t going anywhere. He wants Sam and Dean to treat Cas like family even though they don’t know him.

It’s awkward enough for Sam, so it’s gotta be even harder on Dean.

Dean’s never connected with other kids the way he connects with Sam. He doesn’t really have anyone Sam would call his _friend._ That’s always been Sam, he’s his friend.

He hopes that, at the very least, Dean will open up to the idea of letting Cas be his friend, too.

 

* * *

 

Six months. That’s all it takes. Six months after Dad introduces Amara and Cas they get a marriage license. They get married at the local courthouse with Sam, Dean, Cas, and Amara’s brother, Chuck, as their witnesses. Amara wears a long, black dress and Sam grudgingly admits she looks gorgeous.

While they don’t save up for a nice wedding, they _do_ decide they’re going on a honeymoon - obviously it’s a no-kids-allowed kind of thing.

“You take care of your brothers, Sam. Keep them safe.” Dad pets Dean’s hair with one hand and claps Sam’s shoulder with the other.

“Yes, sir,” Sam says, confused that his Dad would even feel the need to say such a thing. This isn’t new for him. He lives and breathes all the necessary ways to take care of Dean and now he’s doing those things for Cas, too.

Cas raises his arms, face pinching and serious, with a look Sam has very well memorized.

“Up, Sam!”

“In a minute, buddy,” Sam says, shooting Cas a dimpled grin.

Sam has done his best to avoid Amara whenever he can get away with it. The woman isn’t evil incarnate, she isn’t bad at all.

But she’s not Mary and Sam can’t let himself care about her. Not yet.

Dean’s smitten, though. His eyes are full of pure adoration whenever he looks at her, similar to how he looks at Sam and Dad.

It’s not a surprise. Dean’s hungry for a mom and doesn’t remember Mary, the best mom in the fucking world. She died when Dean was just a baby.

Amara is down on Dean’s level, whispering something in his ear and Dean’s practically vibrating from whatever it is that she’s saying to him. Then she’s kissing Dean and Cas goodbye and turning knowing eyes on Sam.

“Thanks, Sam. We really appreciate the help. If you need anything, and I really do mean anything… don’t hesitate to call. You’ve got the number to the hotel we’re staying at.”

“Uh… you’re welcome,” he finally manages. “We’ll be fine.”

Amara stands up then and pulls Sam into a hug, but he doesn’t melt into the contact like Dean and Cas did.

“See you boys in a week. Have fun with Jody and Bobby!”

Sam kinda doubts it’ll be _fun_ , but it shouldn’t be too horrible as long as he’s not cooped up in Bobby’s house the whole time.

 

* * *

 

It’s hell. That’s the cold, hard truth. Watching Cas or Dean would be easy enough, but _both_ for a week? By the end of day one Sam’s already over it. When day three rolls around he’s feeling more than a little grumpy. He wants _off_ this ride.

Jody and Bobby take pity on him, let him go hang out with friends for a few hours. Apparently the only thing Cas says during his absence is Sam’s name over and over and Dean isn’t much better, asking questions incessantly and is moved to tears a time or two.

When Sam returns the boys throw themselves at him as hard as they can and he pretends to lose his balance and topples over on the floor.

“Why’d you go away, Sammy?” Dean asks once Sam’s flat on his back, crowding in close. Cas plops down on Sam’s chest and he can’t help but laugh.

“Was just seeing some friends. I’m back for good, don’t worry.”

“Really?” Dean’s voice is small, eyes red-rimmed.

Guilt stabs him right in the heart - him being gone affected his brothers more than he’d prepared himself for.

“Why don’t you pick a game out for us to play? Anything you want.”

“Yay!” His little brother gives him a painfully big smile and scurries off.

Cas is watching Sam intently, has been through the whole exchange with Dean, and it’s only when Sam touches the toddler’s nose that it seems to break the spell. Cas’s eyes shut and he begins to drift off.

When Dean returns holding _Mr. Bucket_ in his hands his face falls. “I’m tired, too,” he announces and puts the game aside, eagerly moving back to his spot beside Sam.

“All right. Why don’t I get you guys in bed then?”

“No. Right here, Sammy.”

It’s uncomfortable as hell napping on the living room floor, but both of his little brothers are actually happy, so Sam’s not gonna complain.

 

* * *

 

The first time a kid spits in Cas’s hair Sam’s mad enough he wants to close himself off in his room and pound a pillow or a punching bag.

Cas is fucking _harmless_. A quiet, intense, and, okay, he’s totally a weird little boy, but he would never hurt anyone and him getting bullied doesn’t seem fair.

And, okay, Sam’s had his share of bullies. Still does. But he can’t recall ever getting picked on this young, not in fucking _kindergarten_.

It just feels _wrong_.

“Dean,” Sam murmurs, getting down on his knees so he’s on his little brother’s level. He musses his hair and Dean tries to slap his hands away, but Sam knows he secretly loves the attention. The kid still just wants to be close to his big brother.

“You need to keep an eye out for Cas, okay? On the bus, at lunch, whenever you can manage it.”

It wouldn’t be enough, not nearly enough. Dean wouldn’t share any classes with Cas, but something was better than nothing.

Dean has grown used to Cas’s weirdness and they’re even hovering over that line of tentative friendship, so he thinks it shouldn’t be too hard to get him to agree.

“Okay, Sammy,” Dean says, poofing his chest out proudly.

“Don’t punch anybody. Get a teacher involved if kids are being jerks to Cas,” Sam adds and for a brief, fucked up moment he hopes Dean disobeys him.

 

* * *

 

When Sam breaks the news that he’s going to Stanford, the reactions he receives from his brothers are radically different - not that that’s a surprise.

Cas is solemn. He might not understand the specifics and is understandably upset, but at the very least he seems to get that this will make Sam happy.

“You’re gonna forget all about us!” Dean says, voice cracking. It makes him flush with embarrassment. “We’ll probably never see you again.”

Dean looks like he’s about to assault the nearest wall. Sam gently grabs his wrist and tugs him close.

“Hey, take it easy,” Sam says softly. “I’ll be here during every school break. You’ll get phone calls each week. You’ll barely know I’m gone.”

“Shut up, Sam!” Dean growls, but wraps his arms around Sam’s waist. “And fuck you for leaving us.”

“It’s what normal people do when they grow up,” Sam points out, feeling an ugly stab of guilt and regret. “Going to college will make me happy and help me get an awesome job. Don’t you want me to be happy?”

“Yes. But I thought you were happy here! Thought you were happy with us. With _me_.”

“I’m sorry, kiddo,” Sam says and means it.

“Yeah, whatever,” Dean chokes and stumbles from the room, leaving him alone with Cas.

Cas stares at him, wide-eyed.

“He’s gonna try and pull back for awhile. Don’t let him, okay? Keep trying to be his friend. He’s gonna need the company.”

“Yes, Sam.” Cas surges forward and hugs Sam tighter than he ever has before. “It won’t be the same without you.”

“I know.”

If they weren’t so young, if they were closer to Sam’s age and Sam was a little older he’d be tempted to bring his brothers with him - but it’s unthinkable.

He tells their dad goodbye last and John’s response is, “don’t come back.”

Sam’s fairly certain John doesn’t mean it and he’s experiencing intense disappointment just like Dean and Cas are, but it hurts all the same.

 

* * *

 

He should visit, but he can’t bring himself to see John just yet. He doesn’t hate him, but damn is he tired of the same old argument that is brought up every time they talk. Sam isn’t entering the family business and it’s about time his Dad accepts that fact.

Sam sends his brothers letters and they call him whenever the mood strikes. At first all of them are excellent at keeping tabs on each other, but slowly but surely Sam feels like he’s drifting further and further apart from his brothers.

Nearly seven years after leaving home he sees a familiar car in his parking lot - a ‘67 Chevy Impala.

It’s _them._ His brothers came to see him.

He’s out the door to meet them so fast he can hear his roommate Jess laughing at him.

The last time he saw them they were children _._ It’s not rational in the least, but a part of him expects that to still be the case.

And when his eyes actually land on his brothers Sam is _floored._

_Not so little anymore._

Not at all, in fact. They’re full grown and beautiful. Dean’s only a couple inches shorter than Sam now.

_I shouldn’t find my own brothers attractive._

Shouldn’t is the key word here, because he absolutely does.

“H-hey! Holy shit! What are you doing here?”

“That’s not much of a hello, Sammy,” Dean teases, moving in for a hug. It seems wonderfully fitting that he’s wearing an old-looking Batman shirt. “It’s spring break, dude.

“We thought we’d stop by since you never come home to see us,” Cas adds with a smirk.

“Where’s Dad? I can’t believe he let you take Baby -”

“Oh, she’s mine now,” Dean says proudly, backing off so Cas can have a turn to pull Sam close.

Sam keeps the hug with Cas brief, too freaked out by his current thoughts to allow himself the time to hug him properly.

“Are you serious? Holy shit! When did you get her?”

“For my eighteenth birthday,” Dean says, flicking his tongue out between his teeth. “Because I’m gonna be a mechanic like Dad.”

Sam’s not jealous at all - Dean’s more obsessed with Baby than all of them put together. That car _should_ be his. But he _is_ bummed he didn’t get to see the look on Dean’s face when the Impala was given to him.

“That’s great. I’m really happy for you, man. Ah. Did you guys wanna come in and meet my friend Jess?”

“Hell yeah! Is she hot?” Dean winks like an idiot, far too amused for his own good.

Sam rolls his eyes. “I’m not gonna even dignify that with a response.”

“Friend or ‘friend’?” Cas asks and Sam can’t help but notice he’s looking stiff and maybe even unhappy.

_Huh. What the hell is up with that?_

“She’s just a friend,” Sam says. And then, to lighten the mood, “Why? You jealous, Cas?”

Sam hip checks his baby brother and Cas’s face breaks into a grin again.

“Excellent. Yes, I’d very much like to meet your friend, Sam.”

“You didn’t say if you were jealous,” Sam says before he can think better of it.

Cas smiles even wider.

_Weird._

Dean coughs awkwardly. “We gonna head in and meet your hot roommate or what?”

“Yeah.”

Sam turns away from Dean and Cas and leads the way to the apartment, doing his best to ignore the questions in his head.

 

* * *

 

When Sam passes the bar exam he moves back home, wanting to find work close to Cas and Dean. They’re eighteen and twenty, unlikely to want too much to do with him now that they’re all grown up, but just in case, it’s time to suck it up and play nice with their dad so he can see the boys on a regular basis.

Not even a full month after moving into his new apartment, Cas barges into Sam’s place with his backpack.

_Uh oh._

“Hey… what are you doing here? It’s the weekend, shouldn’t you be hanging out with friends?”

“Dean’s driving me insane,” he says like it should be the most obvious thing in the world.

_At least you get to see him._

“Ah, come on. It can’t be that bad,” Sam says as he shuts the front door and leads Cas to his living room.

Sam’s so proud of his little brother, but Dean’s so busy these days he feels like he’s intruding. He’s finally getting a taste of what it had to be like for his little brothers and it’s awful, the way the absence of Dean is affecting him.

Their relationship has improved, has become healthier by leaps and bounds… and yet he can’t stop thinking about how it used to be.

Sam and Dean used to be inseparable and while they are still undeniably connected, things change.

One relationship that hasn’t changed, though, is the bond he shares with Cas - although Sam does wonder if maybe it’s a little creepy having his kid brother here with no one else around.

Cas takes a seat on his couch and places his backpack down carefully on the floor.

“Could I stay here for the night?”

“Uh. I dunno if that’s a good idea...”

He wants to say yes, he wants to say yes so badly. Sam is lonely and he’s _missed_ this - but he can’t get over how it might look to other people if they knew Cas was here.

“Come on, Sam. I don’t have anywhere else to go,” Cas says. His eyes are big and sad, like the very idea that his big brother might turn him down could crush his spirit.

Cas isn’t the type to wear his emotions on his sleeve like this, so it hits Sam especially hard.

“Okay, fine. Whatever you need. But I don’t get it. Thought you and Dean were friends.”

“Best friends,” Cas corrects, stretching out his neck and rolling his shoulders before relaxing into the couch like he fucking belongs here with Sam. “The only one I feel closer to is you, Sam. But Dean’s loud and obnoxious when he’s drunk and I can’t deal with it right now.”

Sam raises a brow. “So you don’t drink, too?”

“Yeah, but I know better than to drink around Dean.” Cas’s face, which has been pinched up until this point, lightens considerably.

“Gets too heated?”

Sam feels so fucking out of the loop and he hates it. These are things he should _know._

“Understatement. We’ve punched each other more than once.”

Sam scoots a little closer, going into Protective Big Brother Mode.

“That’s not okay. Neither of you should be getting violent. Do Mom and Dad know?”

“It hasn’t happened in months,” Cas says, evading the question. “I promise I won’t get physical with him again no matter what he says.”

Sam’s eyes narrow. “If you go back on that I’m gonna have to do something about it. Not gonna have you guys hurting each other.”

“Sam, it really isn’t like that. Things cool off quickly, we’re okay. We’re more than okay. It’s only the drinking that gets irritating.”

“Good. So. Is that why he’s loud and obnoxious tonight then?”

“Dean was whining about me coming over.”

Sam blinks. “Really? Why?”

“No idea,” Cas says with a shrug. “But I told him he was welcome to come along. Then he ignored my invitation and stole a bottle of Mom’s Jim Beam. It escalated from there so I left without him.”

“I thought he was too busy to hang out this month,” Sam says, trying to disguise the hurt so it’s not evident in his voice. “It’s been on purpose, hasn’t it? He’s avoiding me.”

“He’s having a threesome,” Cas deadpans. “With Cassie and Benny. So I wouldn’t say he’s only avoiding you.”

Sam chokes on the coffee he’d been drinking. “Uh, okay. Good for him, I guess. But I really didn’t need to know that.”

“You asked,” Cas points out, a small smirk appearing on his face. “Don’t ask questions you might not be able to handle the answer to.”

“Smartass.”

The smirk widens and he gives Sam a hopeful look. “Do you have any beer or wine or… anything?”

“Not on your life, kiddo. You can have a soda.”

“Don’t call me ‘kiddo’.”

 

* * *

 

 

Sam shouldn’t let this happen.

His baby brother comes over far too often. Almost every weekend they’re alone, plus there’s a family dinner a few times a month. The kid should be hanging out with people his own age, not staying cooped up in Sam’s place while he works on cases.

But the thing is, it’s painfully obvious Cas doesn’t have any friends besides his brothers. While Dean grew out of his awkward phase and became well liked by almost everyone, Cas remains as quiet as ever. He doesn’t fit well enough into any box to be a part of a clique.

Sometimes it seems as though Cas prefers it this way. He certainly doesn’t make a fuss about spending time with Sam.

It doesn’t really hit him that there might be some deeper motive on Cas’s end besides brother bonding until he starts staring at Sam - a lot. Throughout movies, dinner, and even while Sam’s researching and Cas should be busy studying, Sam feels his little brother’s eyes on him.

It’s not innocent staring.

Cas licks his lips, flicks his gaze over Sam’s body, making no effort to hide that he’s checking him out.

It needs to stop.

How exactly does one ask their brother to stop eye fucking them? It’s not a thing he’s prepared himself to ever have to say.

Sam wants to drink in order to gather the courage to speak, but Cas deserves better than that. No, he can wait until he gives Cas the bad news before pulling out the red wine and anything else he can get his hands on.

They’re cooking dinner together when Sam glances at Cas and clears his throat.

“We gotta talk.”

“I’m right here, Sam. Say whatever you want.”

“I don’t think we should spend any more time alone together.”

Cas stops what he’s doing and turns to face Sam completely.

 

 

“What? Why?”

“I’ve been hoping I was just paranoid, but you aren’t exactly subtle.”

“Never have been, Sam. Certainly not when it comes to you. Why does that matter?”

Sam blinks and takes a few steps away from the counter, putting some much needed space between them.

“We’re brothers,” Sam says, getting to the heart of it. “Whatever you’re thinking when you look at me… we can’t. We’re brothers and I’m supposed to protect you.”

“Step brothers. And I don’t need protecting.”

“The fuck, Cas?” Sam frowns, chest aching. “Have I ever treated you any differently than I do Dean? You _are_ my brother, Cas. In all the ways that matter, you’re our brother.”

Cas’s eyes turn dark and Sam’s pulse jumps. “You aren’t treating me like a brother. You’re treating me like someone you want.”

“Wait, what? What are you talking about?”

“You asked me if I was jealous of Jess.”

“Oh my god, that was a _joke._ ”

“When Dean was driving me crazy and you let me stay overnight for the first time, you put a blanket over me and kissed my forehead when you thought I was sleeping.”

“Christ. It was _brotherly._ I was being a good big brother!”

“Were you just being a big brother when you walked in on me in the shower the next morning? I saw you _look_ , I saw how you lingered _way_ longer than most people would that walk in on their brothers.”

“Cas -”

“Tell me you don’t think I’m attractive, that you don’t want me, and I’ll drop it.”

“That - that doesn’t matter!”

“It does.”

“Fuck.” Sam swallows hard, looking for an escape, but finding none. “Yes, okay? Fuck yes. I _do_ find you attractive. I think of you in ways that isn’t brotherly at all. _All_ the time. But that doesn’t mean we should act on it.”

Cas takes a few steps closer to him, the food on the stove forgotten.

“Why not?”

“I used to change your diapers! I helped teach you how to tie your shoes! I gave you kisses before putting bandaids on you when you fell down!”

“I don’t care.”

“You’re just a baby -”

“I’m of age,” Cas interrupts. “I graduated high school, Sam. I’m about to enter my first year of college. I’m not a child anymore.”

“This is sick.”

“I don’t care,” Cas rasps and closes the distance between them. “

Sam groans. “This is a bad idea -”

“Sam? It’s time to shut up,” Cas growls before trapping his big brother against the counter and devouring his mouth.

Sam only pulls away when the smell of burning food begins to fill the kitchen and they’re both throbbing in their pants.

 

* * *

 

 

Despite his begging, Cas comes over again - the night they’re supposed to have dinner with their family, no less.

It’s a bad fucking idea, he knows it deep down to his bones.

But he’s weak. Always has been and always will be, at least when it comes to Cas and Dean.

_Is this my fault?_

That’s a question that won’t leave him be. Surely he’s done _something_ to ruin his little brother, to make him feel and think things no brother should.

“Cas -”

“Don’t,” Cas murmurs, caressing Sam’s lips with a thumb before pushing him flat onto his back on the couch. “Don’t think too hard about this. Enjoy yourself.”

“How can you be so fucking calm right now?”

Cas smirks and pops his jeans open, pulling out his cock and his eyes are on Sam the whole time. “I’ve had time to adjust to what I want from you, Sam. A _long_ time.”

“Oh, god, _do not_ tell me about it.”

Sam’s half mortified, half turned the fuck on. And, oh Jesus, Cas’s _dick._ Who knew a dick could be so perfect?

“Does this look like a baby dick, Sam? Do you still think I’m just a baby?” Cas asks as he strokes himself slowly, making precome leak from the tip of his cock.

“N-no, f-fuck. Your cock sure isn’t anyway,” Sam blurts out and promptly hates himself far more than he ever has before. Cas laughs softly and scoots up his chest until that delicious looking cock of his is hanging over Sam’s face.

“Glad you seem to like it, because I want you to let me fuck your face. I don’t plan on being gentle, so I hope you’re experienced.”

“Are you fucking -”

“Shh.” Cas hushes him by rubbing the head of his dick along Sam’s bottom lip. “Yes, Sam. This is what I want and you’re gonna give it to me. You want it just as much as I do - you can’t hide it, Sam.”

Sam shivers, mouth parting to get a taste of the younger man. He hates how easily Cas has read him, but at the same time it’s a relief. “Where did you get that dirty mouth?”

“Remember what I said earlier? Don’t ask questions unless you actually want the answer.”

“F-fine.”

“Ready?”

Sam’s breath speeds up. “Y-yeah. Do it.”

“Show me how good you can be, Sam.”

“Okay. Fuck.”

He opens his mouth wide and Cas tilts his hips before pressing forward and sliding into his mouth in one fluid motion. The thickness of him, the weight on his tongue is enough to have Sam aching.

He whines and tries to bob his head, but it’s pretty much impossible in this position without being incredibly uncomfortable.

“No,” Cas says firmly, pulling out of Sam’s mouth and he tries to chase the taste of his little brother.

“Stay still, Sam. Be good.”

It’s difficult to fight the urge to mouth off or try to assert dominance over Cas.

He’s not used to getting bossed around.

But it’s better this way. It might cut down on the guilt, the incredible wrongness of this if he’s the one being used. So he gives Cas what he wants and stays completely still unless he’s told to do otherwise.

“Fuck,” Sam whispers after Cas comes, after he greedily swallows every drop.

“Would you like me to take care of you?”

“Please don’t.”

Hurt flashes across Cas’s face and he gets off of Sam. “I don’t understand.”

“I’m sorry,” Sam chokes, sitting up and putting his face in his hands. “I’m so fucking sorry.”

“What for? You didn’t do anything wrong.”

“I did _everything_ wrong. Otherwise this wouldn’t have happened.”

“We’re adults,” Cas reminds him. “What we choose to do is _our_ business.”

Sam shakes his head. “I’m sorry I hurt you.”

“Sam,” Cas says, voice firm. “You didn’t hurt me. You didn’t take advantage of me.”

“You should go,” he says as he gets off the couch and begins to pace. “Get away from me.”

“Are you listening to me, Sam?”

Cas follows him, pressing him up against the nearest wall so he can’t escape without getting physical with his little brother.

It’d be hilarious if it wasn’t so hot. Cas is _tiny_ and yet he tries to throw Sam around like a rag doll.

“C-Cas -”

“I said, are you listening?” Cas demands, hot breath soaking into Sam’s skin.

“I am, but -”

“You just gave me everything, I’m not letting you take it away.”

“What do you mean?”

Cas shakes his head.

“Later. Right now I need to fuck the stupid ideas out of you.”

“F-fuck.”

“Go to your bedroom and start prepping yourself.”

Sam wants to argue, but goddamn he can’t deny he likes the demanding, the expectation that he’ll obey.

“You’re such a little shit.”

“I am. But it’s not gonna stop you from being good for me, is it?”

“No.”

“Then go.”

Sam nods and pushes off the wall to do as he’s told.

Once in the bedroom he eagerly removes his clothes and gets on the bed, pressing his face against the covers and lifting his ass high in the air, thankful for his long arms. Fingering himself is difficult in this position, but not impossible.

Plus, it’ll be worth hearing whatever noise Cas makes when he sees him.

He doesn’t disappoint.

“ _Sam.”_ A groan punches out of him. “Oh, Sam. Thank you.”

The bed dips as Cas gets on top of it and Sam can’t understand why Cas’s touch is gentle as he spreads his cheeks.

“You okay, Cas?”

“Of course I am.”

“I’m all ready for you, don’t even need any lube.”

“I need to be sure.”

Cas grabs the lube anyway and squirts some out onto his cock.

“You gonna, um, hurry up? We’re already late for dinner.”

“This is our first time, Sam. There’s no way we’re having a quickie.”

“What, the blow job doesn’t count?”

“Oh, it does,” Cas rasps, running his hands along Sam’s trembling thighs. “But this is different and deserves thoroughness on my part. I’ll take good care of you, Sam.”

“Y-you’re barely out of high school. Can’t be _that_ experienced. I should be showing _you_ what _I_ can do.”

“Thought you’ve learned your lesson. I prefer topping. I may be young and I might not have had many girlfriends - but I am not a stranger to one night stands.”

That should seriously not be hot.

“Jesus Christ, Cas! You practiced safe sex, right?”

“Stop.”

There he goes with that tone, that sexy fucking voice that makes Sam melt.

“I care about you -”

“This is not the time for a lecture about my sex life.” He presses his generous sized dick against Sam’s hole. “Later, Sam. I’ll answer whatever questions you have later.”

“So quit teasing and fuck me already!”

“Turn over,” Cas demands.

He flips over with an impatient groan and spreading his legs. “There. Satisfied?”

“Not even close.”

Cas pushes Sam’s thighs up to his chest roughly, sinking into him in a long, delicious thrust.

Despite his position Sam does his best to try and fuck himself on Cas’s cock so he could take him in deeper, faster. “God damn.”

“Oh really? That’s all you have to say, hmm?” Cas teases, placing a hand on Sam’s cock so he can stroke it in time to his thrusts.

“P-pretty much.”

“Mm. You’re still able to speak, which means I’m not fucking you properly,” Cas remarks with a wicked grin before pounding into Sam viciously, each thrust shaking the bed.

Sam almost screams and wraps his legs around his little brother, not bothering to try and respond this time.

 

* * *

 

 

Sam wears a plug to the family dinner and regrets it as soon as he sits down. He’s so full of come it’s hard to think about anything else.

“Pass the rolls, dude,” Dean says, frowning at Sam.

He does, biting his lip hard when he shifts in his seat, making the plug rub on his oversensitive prostate and he lets out a soft, barely there whine.

“Sammy?” Dean tenses, adorably concerned.

Cas smirks knowingly and Sam can’t hold back a you’re-in-so-much-trouble kind of glare.

It just makes Cas grin wider.

“I’m all right. Just a little sore,” he finally manages.

“Right.”

Dean doesn’t believe him.

_Fuck._

Thankfully Amara comes back into the room then with the rest of their food - she’s carrying a huge salad and John’s got the turkey.

“Wow. Do you need any help with all that?”

Amara shakes her head. “No, Sam. Pay attention to your brothers.”

“Yeah, Sammy. Don’t worry about it. I helped cook dinner, it’s all good.”

“Okay.”

Amara and John put the food on the table and sit down next to each other. Dad places a hand on top of hers and squeezes gently.

It’s kind of disgusting how in love they are. Disgusting and maybe sweet. He hasn’t decided.

Sam squirms at the display of affection and it’s a bad idea because now his stupid dick is trying to get hard from the attention to his prostate.

Cas, the little shit, is _still_ smirking at Sam and jars his chair with his foot, making him squirm harder.

He’ll be lucky if he doesn’t come in front of everyone at this rate.

Dean shoots him an odd look and Sam rubs at the back of his neck, unable to meet Dean’s gaze. It’s gonna be a long fucking night.

 

* * *

 

 

There’s no good way to say _by the way, our little brother is fucking me._

So he doesn’t.

But it’s starting to look like Dean’s figuring it out all on his own.

Torturing Sam in front of their unsuspecting family is Cas’s all-time favorite activity.

While Amara and John remain unconcerned, Dean watches them carefully at every family meal when they’re all together, gaze unwavering. He takes in each movement, each word they say to each other.

Dean barely even touches his food these days.

He can’t bring it in himself to ask Dean why and he certainly can’t bring himself to tell the truth.

He knows it’s the logical choice, keeping the secret locked up tight. He knows it won’t help anyone.

_I don’t owe him anything._

But he feels fucking horrible.

 

* * *

 

These days Sam offers himself up to Cas, _inviting_ his brother to touch him. It’s gone from Cas almost forcing himself onto Sam, to Sam seducing his baby brother every chance he gets without incessant guilt gnawing at him.

Now is no different.

Okay, maybe there’s a _little_ guilt, but it’s not even tied to Cas at this point and is more about the confusing shit with Dean. He can’t let himself think about that right now, though.

Cas will be showing up any minute now and Sam’s naked and stuffed full with the biggest fucking plug he owns, a move guaranteed to drive Cas up the wall. He’s also holding a key to his apartment that he plans on handing over when his brother walks in the door, and yeah. He’s starting to second guess this idea entirely.

It’s been four months and they’ve started to settle into their little arrangement. He’s hesitant to put a label on what they have. And, obviously, he doesn’t want to scare Cas away. It wasn’t all that long ago that Cas was in high school, after all. This feels like a lot to ask someone so young.

At the same time his feelings aren’t going away and he _needs_ to make this next move, to show Cas just how much he means to him.

It’s then that the doorknob turns, interrupting Sam’s thoughts. And then the door is _open_ and Cas is _there._

“Oh shit,” Cas breathes and quickly shuts the door. “I thought you’d made dinner? Not that I mind you being naked, but what -”

“I have something for you,” Sam says, and opens his hand so Cas can see the key on his sweaty palm. “Want it?”

“S-Sam?” His little brother strokes his fingers along the key, but doesn’t pick it up.

“Before you ask me if I’m sure, the answer is fucking _yes._ I wouldn’t be showing it to you if I wasn’t. But don’t let that influence your decision at all. I want you to be comfortable. I want you in my life, okay? I don’t care what capacity it is, I just want you _here_ -”

Cas’s head snaps up and he stares at him with a look that’s so intense it knocks the breath right out of Sam.

“I want it, Sam. I’ll make your whole body know that I want it.”

Cas follows through with his promise by fucking Sam right there on the floor next to the front door.

 

* * *

 

He’s in Cas’s bedroom when it happens. Dean comes into the room without knocking and catches Cas with his hand down Sam’s pants.

It’s fucking stupid and all his fault for not locking the goddamn door.

“U-uh! I can explain,” Sam says, holding up his hands in surrender.

Dean storms over, getting right into Sam’s space, close enough he can feel his hot breath on his face.

“Our baby _brother_ ?” Dean hisses, eyes wild as he drags Sam away from Cas. He looks about ready to bash Sam’s face in. No. He looks ready to cry, looks like a wounded animal, and that’s worse. “How _could you_?”

“Dean, stop!” Cas looks just as angry as Dean. Hell, he looks _angrier_. “You don’t get to touch Sam if you plan on hurting him.”

“Oh, I’m not gonna hurt him - I’m gonna kill him!”

Sam doesn’t try to fight back. There’s still a part of him that thinks he deserves to be punished.

But that doesn’t mean he wants Cas to have a ticket to that show.

“I know this is a lot to take in -”

“A lot to take in? A lot to take in? Sam, his hand was in the _back of your pants._ You were letting him _finger you!_ What the actual fuck is wrong with you?”

Sam cringes. “I’m s-sorry.”

“Dean. If you don’t get the hell away from Sam, there’s going to be a problem. Got it? I’m an adult and this is none of your fucking business.”

“You’re my little brother and I gotta look out for you,” Dean says, sounding less sure of himself this time.

“I’m the youngest, yes, but I’m still an adult. It’s up to _me_ to decide who I’m involved with and who I’m not - you don’t get to make that call.”

“I gave him a key to my apartment,” Sam adds weakly. “This really isn’t what you think at all.”

Dean makes a noise like he’s been punched in the gut and stumbles back a couple feet.

“You know what? Fine. Go ahead - have each other. I don’t care anymore,” Dean says acidly and stalks out of the room.

The whole situation is upsetting, but the _I don’t care anymore_ is what plays an incessant loop in Sam’s head after Dean’s out of sight.

 

* * *

 

 

“Did I tell you what happened a few nights ago?”

Sam slides off of Cas, chest heaving from the sweaty and athletic sex they’d just had, his body ready for sleep - but now his brain isn’t. Ice-cold fear floods him at Cas’s words.

“No, what?”

“He’s hardly sleeping. And when he does, well, lately he’s been having nightmares.”

“Are you fucking serious?”

“Yes. He was screaming and crying in his sleep. It scared the shit out of me, but when I went into his room to see if he was okay he told me to leave.”

“Oh my god. This is all my fault.”

_He’s hurt, I hurt him. I fucked him up for life._

“No, Sam.” Cas turns over on his side and reaches out to touch his arm. “He was bound to find out eventually.”

“We didn’t have to be so reckless.”

“Come on, Sam. You have to admit it’s been hot.”

“Yeah. It has been. But I can’t fucking ignore this, Cas. What do I do? How do I make it better?”

“Hopefully with time he’ll realize it’s not some fling, that you aren’t taking advantage of me -”

Sam barks out a humorless laugh. “And if he doesn’t?”

“At least we’ll still have each other.”

 

* * *

 

Amara and John are out of town and Cas coaxes Sam into staying the night at their parents’ place with him.

Considering Dean knows every dirty little secret between them, this seems like a horrible plan. Plus, Sam’s got a perfectly acceptable apartment, why create unnecessary tension?

Then again his brother is scaring the shit out of him with the nightmares he’s been having and Sam _aches_ to see with his own eyes how Dean is doing.

Dean makes it a non-issue, though. He decides to go out for the evening, so Sam and Cas will have the place to themselves - at least, according to Cas.

“It’ll be fun,” Cas says as they make their way to the living room.

“What if Dean comes home early and catches us?”

“If you’re worried about him hurting you -”

“I’m not,” Sam disagrees, moving toward the couch. “I’m afraid of Dean hurting _himself._ ”

Cas frowns. “We can’t force him to open up and, quite frankly, after how he treated you -”

“I don’t wanna hear this. I didn’t come over here so you could talk shit about Dean. We fucked up, Cas. Have some empathy, please.”

“I’m sorry, Sam,” Cas sighs, shaking his head.

Sam quirks a brow. “You sure?”

“I’m sorry you’re caught in the middle,” he clarifies. “I can’t apologize for being frustrated, but I _do_ apologize for how I’ve dealt with that frustration.”

“Right, I hear you.” Sam reaches for the remote so he can turn the TV on for background noise. Then he lays down, pulling Cas on top of him.

“Unless you want me to take you right on our parents’ couch, I highly suggest you let go of me, because that’s what’s about to happen.”

Sam bites back a grin and holds Cas even tighter, in the back of his mind aware this is wrong on far too many levels to count, but it doesn’t stop him.

_Dean won’t see us. He isn’t here._

Cas growls and there’s a struggle as he begins to reposition himself so he can unbutton Sam’s pants.

“You know, you’re only in charge because I let you be. If I wanted to, I’d have you on your hands and knees begging for my cock in seconds,” Sam says, purposely trying to rile his baby brother up, because the more he teases him the harder he fucks him.

“You were made to be my bitch, Sam. Not the other way around,” Cas retorts, a small smirk playing on his lips as he succeeds in pulling Sam’s pants down his legs.

“Guess we’re gonna have to agree to disagree on that.”

Cas licks his lips, eyes dark and predatory.

“Sure. Sam… we’re going to try something different today.”

“U-uh. Define different?”

“I’m going to lick your ass.”

“What? Why the fuck would you wanna do that?”

“Haven’t you tried it, Sam?”

“On _other_ people,” he admits. “It’s… okay. I prefer licking pussy or sucking cock. And I definitely haven’t let anyone taste _my_ ass.”

“Well, I love all aspects of foreplay, Sam. Rimming included. So I’d greatly appreciate if you at least let me try - if you hate it, of course I’ll stop. But I don’t think you will.”

“All right, fine.”

One thing that absolutely hasn’t changed is Cas’s ability to get Sam to do almost anything. He’ll probably always be wrapped around Cas’s fingers, eager to do his bidding.

Cas nods and tugs Sam’s boxers down, exposing his cock, tip already leaking precome.

“Let me see you,” Cas breathes.

Sam’s dick jerks and he nods, lifting his legs up out of the way.

Cas fucking _dives_ down with a near feral noise, hot tongue prodding at his hole until it slips inside and begins to tongue fuck him just like that.

“O-oh _f-fuck!_ ” Sam’s voice breaks like a fucking teenager, which should be all kinds of mortifying, but honestly it’s hard to focus on anything other than the sweet tongue buried deep in his ass. “Y-you’re way too good at this.”

He may have heard a snort, but otherwise Cas makes no effort to respond - not that Sam is surprised. His little brother is a man on a mission and his mission is apparently to turn Sam into a helpless mess.

Cas is succeeding with maddening ease.

It doesn’t help that Cas is making no moves to to further things along. He seems perfectly content to tongue fuck Sam’s ass all night and Sam would really rather it move beyond that.

He doesn’t see him until he lifts his head to try and get a better view of what Cas is doing to him - Dean’s standing a few feet away from them.

“What! Fuck! _Dean,_ what are you doing here?” Sam yelps.

Dean doesn’t answer.

He also doesn’t take his eyes off of them.

Sam tries to buck Cas off of him, but Cas won’t budge. “Come on, get off of me! Dean’s fucking here!”

“He knows,” Dean rasps. “He caught me watching long before you did.”

“What the fuck, that makes no sense. We scarred you, gave you nightmares -”

“You sure about that, big brother?”

It’s then that he sees the front of Dean’s jeans getting dark. His glassy eyes and flushed cheeks.

_Oh my god._

It’s difficult to process when Cas is still busy fucking him as deep as he can with his tongue, but it comes together then and Sam can’t hold back any longer - he comes with both of his brother’s names on his tongue.

“You jerked off while watching us, didn’t you?” he asked once he’d caught his breath, finally succeeding in pushing Cas off. “And _you_ ! Why the fuck didn’t you _say_ anything, Cas?”

Cas gives Sam a shiteating grin as he helps him sit up then side-eyes Dean, and Sam’s momentarily distracted by his baby brother’s messy hair. “My mouth was a bit preoccupied and I preferred to keep it that way. Dean… are you going to tell us what the hell is going on?”

Dean adjusts his cock in his jeans and clears his throat. “Here’s the thing. I was never disgusted by what you guys were doing.” He takes a deep breath, eyes wandering the room instead of focusing on their faces. “I was jealous. If you were gonna go there with one of us, it should have been _me._ ”

“Dean…” He gets off the couch, uncaring of his nakedness, and moves over to his little brother. “Why didn’t you fucking say anything back when you found out?”

“What was I supposed to say? I felt like you’d made your decision and it wasn’t me. It fucking sucked.”

“Dean.” He takes a deep, shaky breath. “I didn’t choose Cas over you. I swear I didn’t. If I knew how you felt…”

“Wait a second.” Dean’s gaze connects with Sam’s, his mouth falling open. “You want me?”

“Would I be standing here with my dick out if I didn’t? Come on, Dean.” He reaches out and runs his fingers through his little brothers hair, much like he did when they were kids. “Yes. I want you, but I’m not giving Cas up. We’re together and that’s not changing. Can you handle that, Dean?”

Dean and Cas exchange looks, eying each other up and down. Cas hasn’t made any move to get off the couch, but he seems far from upset.

“If Dean can handle it, I can. Hell, I wouldn’t mind touching _him_ if you’d like to have a threesome.”

“One thing at a time, bucko,” Dean’s quick to say. “Still kinda see you as an annoying kid brother, but I can admit you’re fucking hot.”

Cas barks out a laugh. “Oh, _I’m_ the annoying one? You’re hilarious.”

“I know I am -”

“Guys! Shut up.” Sam pulls Dean in for a kiss that’s all teeth, tongue and _fucking._ He _owns_ his little brother’s mouth and Dean melts against him, making him feel powerful.

Cas groans and it’s not long before Sam can feel his baby brother - _partner_ \- pressing up behind him, dick rubbing against his ass as Sam makes quick work of Dean’s pants.

“So you weren’t bluffing, I see,” Cas says, resting his chin on Sam’s shoulder as he takes it all in.

“You have a little dominance in you, after all. Either that or Dean’s the neediest bottom I’ve ever seen.”

“Both,” Dean gasps, pulling away so he can wriggle the rest of the way out of his pants.

As soon as they’re off Sam’s on him again, wrapping an arm around his brother, pressing a finger between his ass cheeks so he can tease at his hole. He doesn’t try to penetrate him, he wouldn’t do that without lube - he just wants to make Dean whine.

He gets his wish. Dean lets out sweet little mewls and it’s quickly getting him ready for round two despite having just come.

Sam has no fucking clue how they’re gonna keep this away from Mom and Dad, but right now it doesn’t matter because he finally feels like he’s home.

He’s home and he’s _whole._

**Author's Note:**

> I'm samanddeaninpanties on tumblr if you wanna chat!

**Works inspired by this one:**

  * [Whole [Artwork]](https://archiveofourown.org/works/8946994) by [casquecest](https://archiveofourown.org/users/casquecest/pseuds/casquecest)




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